Liquid level detector

• US 20070234796A1
• Filed: 02/14/2006
• Published: 10/11/2007
• Est. Priority Date: 02/14/2006
• Status: Active Grant

• Current Assignee: Savannah River Nuclear Solutions LLS
• Original Assignee: Savannah River Nuclear Solutions LLS
• Inventors: Tshishiku, Eugene
• Granted Patent: US 7,992,437 B2
• Time in Patent Office: Days
• US Class Current: 73/290.R
• CPC Class Codes: G01F 23/0007 for discrete indicating and measuring G01F23/02 - G01F23/28 take precedence
• CPC Class Codes: G01F 23/241 for discrete levels
• CPC Class Codes: G01F 23/242 Mounting arrangements for electrodes

Abstract

A liquid level detector for conductive liquids for vertical installation in a tank, the detector having a probe positioned within a sheath and insulated therefrom by a seal so that the tip of the probe extends proximate to but not below the lower end of the sheath, the lower end terminating in a rim that is provided with notches, said lower end being tapered, the taper and notches preventing debris collection and bubble formation, said lower end when contacting liquid as it rises will form an airtight cavity defined by the liquid, the interior sheath wall, and the seal, the compression of air in the cavity preventing liquid from further entry into the sheath and contact with the seal. As a result, the liquid cannot deposit a film to form an electrical bridge across the seal.

Claims

1. A liquid level detector for use in containers of electrically conductive liquids wherein said detector is installed vertically comprising:

a) a sheath having an open lower end defined by a rim for contacting a liquid;

b) at least one vertically extending notch in said rim;

said notch terminating in a shoulder at its upper end;

c) an electrically conductive probe positioned within said sheath and being spaced apart therefrom, said probe having a tip positioned vertically between said rim and the shoulder of said notch;

d) an insulating seal between said probe and said sheath hermetically sealing the tube at a predetermined distance vertically above the tip of said probe, said seal holding and positioning said probe within said sheath;

e) a first electrical conductor connected to the upper end of said probe and a second electrical conductor for electrically establishing a conductive path with a liquid into which said probe may be inserted, each of said conductors being adapted to be connected to a module for sensing a complete circuit between the probe and liquid.

2. The detector of claim 1 wherein said probe is a first probe and including a second probe positioned within said sheath at the same vertical height as the first probe, the second probe being insulated from the first probe and from the sheath wall by an insulating seal and said second conductor being connected to said second probe instead of the tank wall.

3. The detector of claim 1 wherein a plurality of notches are positioned equidistant around said rim.

4. The detector of claim 3 wherein the outer wall of the sheath immediately above said rim tapers inwardly and terminates in said rim.

5. In the method of determining liquid level in a tank by using a vertically installed liquid level detector, said detector including a probe having a tip at its lower end deposed within a sheath having upper and lower ends, said lower end terminating in a rim, said probe being electrically insulated from said sheath, the improvement comprising the steps of:

a) providing a series of notches around said rim, said notches having an open lower end and upper end terminating in a shoulder;

b) positioning the tip of the probe so that tip is below said shoulder and above said rim;

c) providing an insulating, hermetic seal between the sheath wall and the probe, said seal being spaced apart from and above said shoulder a pre-determined distance sufficient to create an air cavity whereby when the level of liquid within the tank contacts said probe and rises above said shoulder further upward movement of liquid within the sheath will be prevented by the compression of air within said cavity consequently preventing liquid contact with said seal.

6. The method of claim 5 including the step of providing a tapered sheath wall immediately above said rim.